Composite active material and preparation method thereof, solid-state battery monomer, battery device and power utilization device

Abstract

The invention relates to a composite active material and a preparation method thereof, a solid-state battery monomer, a battery device and a power utilization device. The solid-state battery monomer comprises a current collector and a film layer arranged on the surface of at least one side of the current collector, and the film layer comprises a composite active material and sulfide solid-state electrolyte; the composite active material comprises an inner core and a coating layer, wherein the coating layer coats at least part of the surface of the inner core; the coating layer comprises a selenium-containing compound, the chemical formula of the selenium-containing compound is SeaMb, M comprises at least one of Li, Na, K, Mg, Ca, S, Mo, Cr, Zn, In, Ga, Co and Mn, a is greater than 0 and less than or equal to 5, and b is greater than 0 and less than or equal to 20. According to the embodiment of the invention, the cycling stability and the first coulombic efficiency of the solid-state battery monomer can be improved.

Description

Technical Field

[0001] This disclosure relates to the field of batteries, and in particular to a composite active material and its preparation method, a solid-state battery cell, a battery device, and an electrical device. Background Technology

[0002] In solid-state battery cells, the components are in solid-solid contact, and the gaps between these components hinder interfacial charge transport. Therefore, improving the cycle stability and initial coulombic efficiency of solid-state battery cells is a pressing issue that needs to be addressed. Summary of the Invention

[0003] This disclosure provides a composite active material and its preparation method, a solid-state battery cell, a battery device, and an electrical device, which can improve the cycle stability and initial coulombic efficiency of the solid-state battery cell.

[0004] In a first aspect, this disclosure provides a solid-state battery cell, including a current collector and a film layer disposed on at least one surface of the current collector. The film layer includes a composite active material and a sulfide solid electrolyte. The composite active material includes a core and a coating layer, the coating layer coating at least a portion of the surface of the core. The coating layer includes a selenium-containing compound with the chemical formula Se. a M b M includes at least one of Li, Na, K, Mg, Ca, S, Mo, Cr, Zn, In, Ga, Co and Mn, where 0 < a ≤ 5 and 0 < b ≤ 20.

[0005] The composite active material of this disclosure includes a core and a coating layer disposed on at least a portion of the surface of the core. By providing a selenium-containing compound in the coating layer of the composite active material, and utilizing the good compatibility between the selenium-containing compound coating layer and the sulfide solid electrolyte, the direct contact between the core and the sulfide solid electrolyte can be reduced, thereby reducing the decomposition of the sulfide solid electrolyte and improving the cycle stability and first coulombic efficiency of the solid-state battery cell.

[0006] In some embodiments, the selenium-containing compound includes one or more of sulfur selenium compounds, molybdenum selenium compounds, and antimony selenium compounds.

[0007] The aforementioned selenium-containing compounds exhibit good compatibility with sulfide solid electrolytes, do not react with them, and when coated on the surface of the positive electrode active material, reduce direct contact between the positive electrode active material and the sulfide solid electrolyte, thus reducing the decomposition of the sulfide solid electrolyte and further improving the cycle stability and initial coulombic efficiency of the solid-state battery cell. Selenium-containing compounds possess certain electronic and ionic conductivity; using them as a coating layer allows for good charge exchange between the positive electrode active material and other components in the positive electrode film, thereby reducing the impact of the coating layer on the solid-state battery cell capacity. Furthermore, selenium-containing compounds are relatively soft and have good thermal stability, which can buffer the volume expansion of the positive electrode active material during cycling, improving the cycle stability of the solid-state battery cell at both room temperature and high temperature.

[0008] In some embodiments, the sulfur-selenium compound includes SeS2, Se5S, SeS, Se5S2, Se3S2, Se3S5, SeS7, and SeS. 20 One or more of them.

[0009] In some embodiments, the selenium-containing compound content is 0.5%-5% by mass, optionally 0.5%-2%, based on 100% of the total mass of the composite active material. By adjusting the mass content of the selenium-containing compound, the thickness of the coating layer can be adjusted, which can further improve the conductivity of the composite active material, thereby further improving the cycle stability and first coulombic efficiency of the solid-state battery cell.

[0010] In some embodiments, the thickness of the coating layer is 1-100 nm.

[0011] In some embodiments, the thickness of the coating layer is 5-20 nm.

[0012] When the thickness of the coating layer is within the above range, the ionic conductivity and electronic conductivity of the coating layer can be improved, the impedance of the solid-state battery cell can be reduced, and thus the cycle stability and first coulombic efficiency of the solid-state battery cell can be further improved.

[0013] In some embodiments, the specific surface area of ​​the composite active material is 1.3-3.5 m². 2 / g.

[0014] In some embodiments, the volumetric particle size distribution Dv50 of the composite active material is 2-8 μm.

[0015] The specific surface area and / or volume particle size distribution of the composite active material within the above range can improve the ionic conductivity and electronic conductivity of the coating layer and reduce the impedance of the solid-state battery cell.

[0016] In some embodiments, the electronic conductivity of the composite active material is 8-18 mS / cm, and the ionic conductivity of the composite active material is 0.1-1 mS / cm.

[0017] In some embodiments, the compaction density of the composite active material is 1-3 g / cm³. 3 This can improve the stacking performance of composite active materials, thereby further enhancing the cycle stability and initial coulombic efficiency of solid-state battery cells.

[0018] In some embodiments, the electronic conductivity of the coating layer is 0.1-1 mS / cm, and the ionic conductivity of the coating layer is 0.01-0.1 mS / cm.

[0019] Secondly, this disclosure provides a method for preparing a composite active material, comprising: providing a material including a core; mixing the material including the core and a coating material and then ball milling the mixture to obtain the composite active material; the composite active material includes a core and a coating layer, the coating layer coating at least a portion of the surface of the core; the coating layer includes a selenium-containing compound, the selenium-containing compound having the chemical formula Se. a M b M includes at least one of Li, Na, K, Mg, Ca, S, Mo, Cr, Zn, In, Ga, Co and Mn, where 0 < a ≤ 5 and 0 < b ≤ 20.

[0020] Ball milling allows for the uniform coating of materials onto the core surface, improving the uniformity of the coating layer. Furthermore, ball milling directly coats selenium compounds onto the core surface, increasing the purity of the selenium compounds in the coating layer. This further enhances the cycle stability and initial coulombic efficiency of solid-state battery cells.

[0021] In some embodiments, the selenium-containing compound content is 0.1%-10% based on the total mass of the composite active material (100%).

[0022] By setting the mass content of selenium-containing compounds in the coating layer within the above-mentioned range, the thickness of the coating layer can be adjusted, thereby improving the electrical conductivity of the composite active material.

[0023] In some embodiments, the selenium-containing compound content is 0.5%-2% based on the total mass of the composite active material (100%).

[0024] By setting the mass content of selenium-containing compounds in the coating layer within the aforementioned range, the thickness of the coating layer can be adjusted, further improving the conductivity of the composite active material, thereby further enhancing the cycle stability and initial coulombic efficiency of the solid-state battery cell.

[0025] In some embodiments, in the step of mixing the core material and the coating material and then ball milling them, the ball milling speed is 300-1000 rpm.

[0026] In some embodiments, in the step of mixing the core material and the coating material and then ball milling them, the ball milling time is 3-9 hours.

[0027] Setting the ball milling speed and / or time within the above range can make the coating material more uniformly coated on the surface of the core.

[0028] In some embodiments, in the step of mixing the core material and the coating material and then ball milling them, the ball milling process is performed in an intermittent manner.

[0029] Ball milling generates heat. Intermittent ball milling can dissipate this heat and reduce side reactions caused by excessively high temperatures during the ball milling process.

[0030] Thirdly, this disclosure provides a composite active material, which is prepared by the preparation method of the second aspect of this disclosure.

[0031] Fourthly, this disclosure provides a battery device including a plurality of solid-state battery cells according to the first aspect of this disclosure.

[0032] Fifthly, this disclosure provides an electrical device, including the battery device of the fourth aspect of this disclosure. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are merely some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of one embodiment of the solid-state battery cell disclosed herein.

[0035] Figure 2 This is a schematic diagram of one embodiment of an electrical device that uses the battery device disclosed herein as a power source.

[0036] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0037] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the composite active material and its preparation method, solid-state battery cell, battery device, and power-consuming device of this disclosure. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter of the claims.

[0038] The "range" disclosed in this disclosure is defined by a lower limit and an upper limit, whereby a given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this disclosure, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0039] Unless otherwise specified, all embodiments and optional embodiments of this disclosure may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the content of this disclosure.

[0040] Unless otherwise specified, all technical features and optional technical features of this disclosure can be combined to form new technical solutions, and such technical solutions should be considered to be included in the content of this disclosure.

[0041] Unless otherwise specified, all steps in this disclosure may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0042] In this disclosure, the terms "multiple" or "a variety" refer to two or more kinds.

[0043] Unless otherwise stated, the test temperature for all parameters mentioned in this disclosure is 25°C.

[0044] The solid-state battery cells mentioned in the embodiments of this disclosure can independently perform charge and discharge functions. Solid-state battery cells can be cylindrical, cuboid, or other shapes, and the embodiments of this disclosure are not limited in this respect. Figure 1 This is an example of a rectangular solid-state battery cell 5.

[0045] The battery apparatus mentioned in the embodiments of this disclosure may include one or more solid-state battery cell assemblies for providing voltage and capacity. The solid-state battery cell assembly may include multiple solid-state battery cells, which are connected in series, parallel, or mixed connections via busbars.

[0046] In some embodiments, a solid-state battery cell assembly is typically formed by arranging multiple solid-state battery cells. As an example, a solid-state battery cell assembly can be a battery module, which is formed by arranging and fixing multiple solid-state battery cells together to form a single module. As an example, a battery module can be formed by bundling multiple solid-state battery cells together with cable ties.

[0047] In some embodiments, the battery device may be a battery pack, which may include a housing and one or more solid-state battery cell assemblies housed within the housing. As an example, the solid-state battery cell assembly may be a battery module, which can be housed within the housing by securing the battery module to the housing. Alternatively, as an example, the solid-state battery cell assembly may be housed within the housing by directly securing multiple solid-state battery cells to the housing.

[0048] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the solid-state battery cell assembly. Here, "closed" refers to covering or closing, which can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0049] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0050] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0051] The technical solutions described in this disclosure are applicable to various electrical devices that use solid-state battery cells or battery devices, such as, but not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. Solid-state battery cells and battery devices are used to store or provide electrical energy.

[0052] Figure 2 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0053] In a solid-state battery cell, the components are in solid-solid contact, and there are gaps between the components. During cycling, the volume change of the active material will further lead to the expansion of the interfacial gaps, which will increase the impedance of the solid-state battery cell, limit the capacity and reduce the cycle stability.

[0054] In addition, side reactions exist between the active material and the sulfide solid electrolyte, which can lead to the breakage of the active material and the oxidative decomposition of the sulfide solid electrolyte. These conditions can also deteriorate the initial coulombic efficiency and cycle stability of solid-state battery cells.

[0055] In view of this, the present disclosure provides a solid-state battery cell, including a current collector and a film layer disposed on at least one side surface of the current collector, the film layer including a composite active material and a sulfide solid electrolyte;

[0056] The composite active material includes a core and a coating layer, wherein the coating layer covers at least a portion of the surface of the core;

[0057] The coating layer includes a selenium-containing compound with the chemical formula Se. a M bM includes at least one of Li, Na, K, Mg, Ca, S, Mo, Cr, Zn, In, Ga, Co and Mn, where 0 < a ≤ 5 and 0 < b ≤ 20.

[0058] In the case where the current collector and the membrane layer are used as the positive electrode, the current collector can be a positive electrode current collector, the membrane layer can be a positive electrode membrane layer, the composite active material can be a composite positive electrode active material, and the core can be a positive electrode active material.

[0059] The composite active material of this disclosure includes a core and a coating layer disposed on at least a portion of the surface of the core. By providing a selenium-containing compound in the coating layer of the composite active material, and utilizing the good compatibility between the selenium-containing compound coating layer and the sulfide solid electrolyte, the direct contact between the core and the sulfide solid electrolyte can be reduced, thereby reducing the decomposition of the sulfide solid electrolyte and improving the cycle stability and first coulombic efficiency of the solid-state battery cell.

[0060] In some embodiments, the selenium-containing compound may include one or more of sulfur selenium compounds, molybdenum selenium compounds, and antimony selenium compounds.

[0061] The aforementioned selenium-containing compounds exhibit good compatibility with sulfide solid electrolytes, do not react with them, and when coated on the surface of the positive electrode active material, reduce direct contact between the positive electrode active material and the sulfide solid electrolyte, thus reducing the decomposition of the sulfide solid electrolyte and further improving the cycle stability and initial coulombic efficiency of the solid-state battery cell. Selenium-containing compounds possess certain electronic and ionic conductivity; using them as a coating layer allows for good charge exchange between the positive electrode active material and other components in the positive electrode film, thereby reducing the impact of the coating layer on the solid-state battery cell capacity. Furthermore, selenium-containing compounds are relatively soft and have good thermal stability, which can buffer the volume expansion of the positive electrode active material during cycling, improving the cycle stability of the solid-state battery cell at both room temperature and high temperature. Here, "room temperature" typically refers to 20-30℃, and "high temperature" typically refers to 45-80℃.

[0062] In some embodiments, the sulfur-selenium compound may include SeS2, Se5S, SeS, Se5S2, Se3S2, Se3S5, SeS7, and SeS. 20 One or more of them.

[0063] In some embodiments, the sulfur-selenium compound may include SeS2.

[0064] SeS2 combines the high specific capacity of sulfur (S) with the high conductivity of se, thereby further improving the electronic and ionic conductivity of the coating layer. This facilitates good charge exchange between the positive electrode active material and other components in the positive electrode film, reducing the impact of the coating layer on the capacity of the solid-state battery cell. SeS2 is relatively soft and has good thermal stability, which can buffer the volume expansion of the positive electrode active material during cycling, improving the cycle stability of the solid-state battery cell at both room temperature and high temperature. Furthermore, SeS2 has good compatibility with sulfide solid electrolytes; using SeS2 as a coating layer for the positive electrode active material can also reduce the decomposition of sulfide solid electrolytes.

[0065] In some embodiments, the volumetric particle size distribution Dv50 of the sulfur-selenium compound can be 5-200 nm, optionally 5-50 nm. This can further improve the uniformity of coating, thereby further improving the cycle stability and initial coulombic efficiency of the solid-state battery cell.

[0066] In some embodiments, the selenium-containing compound content can be 0.5%-5% by mass, preferably 0.5%-2%, based on the total mass of the composite active material as 100%. For example, it can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.5%, 3%, 3.5%, 4%, 5%, or any range of the above values.

[0067] The thickness of the coating layer can be adjusted by regulating the mass content of selenium-containing compounds, which can further improve the conductivity of the composite active material.

[0068] In some embodiments, the coating layer may be located on 90% to 100% of the surface of the positive electrode active material. Optionally, the coating layer is located on 100% of the surface of the positive electrode active material.

[0069] In some embodiments, the selenium-containing compound content in the coating layer is 100%. This allows for full coating of the positive electrode active material by the selenium-containing compound, reducing direct contact between the core and the sulfide solid electrolyte, reducing the decomposition of the sulfide solid electrolyte, and thus further improving the cycle stability and initial coulombic efficiency of the solid-state battery cell.

[0070] In some embodiments, the thickness of the coating layer can be 1-100 nm, for example, it can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, or any range of the above values.

[0071] In some embodiments, the thickness of the coating layer can be 5-20 nm.

[0072] When the thickness of the coating layer is within the above range, the ionic conductivity and electronic conductivity of the coating layer can be improved, the impedance of the solid-state battery cell can be reduced, and thus the cycle stability and first coulombic efficiency of the solid-state battery cell can be further improved.

[0073] In some embodiments, the specific surface area of ​​the composite active material can be 1.3-3.5 m². 2 / g.

[0074] Specific surface area can be measured using the nitrogen adsorption specific surface area analysis method according to GB / T19587-2017, and calculated using the BET (Brunauer Emmett Teller) method. The testing instrument can be the Tri-Star 3020 specific surface area and pore size analyzer from Micromeritics, USA.

[0075] In some embodiments, the volumetric particle size distribution Dv50 of the composite active material can be 2-8 μm.

[0076] The volumetric particle size distribution (Dv50) of composite active materials can be determined using a laser particle size analyzer (such as the Malvern Mastersizer 3000) in accordance with GB / T 19077-2016. The physical definition of Dv50 is the particle size corresponding to a cumulative volumetric distribution percentage of 50% for the material.

[0077] The specific surface area and / or volume particle size distribution of the composite active material within the above range can improve the ionic conductivity and electronic conductivity of the coating layer and reduce the impedance of the solid-state battery cell.

[0078] The composite active material of this disclosure has high electronic conductivity and ionic conductivity.

[0079] In some embodiments, the electronic conductivity of the composite active material can be 8-18 mS / cm, and the ionic conductivity of the composite active material can be 0.1-1 mS / cm.

[0080] In some embodiments, the compaction density of the composite active material can be 1-3 g / cm³. 3 .

[0081] The compaction density can be determined according to standard GB / T24533-2009 using an electronic pressure testing machine (e.g., UTM7305). An exemplary test method is as follows: Weigh 1g of the above-mentioned composite active material and add it to a container with a base area of ​​1.327cm². 2In the mold, pressure is applied to 40kN and held for 30s, then pressure is released and held for 10s. The compaction density of the composite active material under 40kN pressure is then recorded and calculated.

[0082] When the compaction density of the composite active material is within the above range, the stacking performance of the composite active material can be improved, thereby further improving the cycle stability and first coulombic efficiency of the solid-state battery cell.

[0083] In some embodiments, the electronic conductivity of the coating layer can be 0.1-1 mS / cm, and the ionic conductivity of the coating layer can be 0.01-0.1 mS / cm.

[0084] In some embodiments, the positive electrode active material may include one or more of lithium cobalt oxide and its modified materials, lithium iron phosphate and its modified materials, lithium manganese iron phosphate and its modified materials, lithium nickel cobalt manganese oxide and its modified materials, lithium nickel cobalt aluminum oxide and its modified materials, lithium nickel oxide and its modified materials, lithium manganese oxide and its modified materials, lithium niobate and its modified materials, lithium titanate, sulfur, selenium, and tellurium. The modified materials for the above-mentioned positive electrode active materials may be those obtained by doping and / or surface coating modification of the positive electrode active material.

[0085] As an example, positive electrode active materials may include, but are not limited to, LiCoO2 and LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811), LiNi 0.96 Co 0.02 Mn 0.02 O2 (abbreviated as Ni96), LiNi 0.80 Co 0.15 Al 0.05 O2, LiFePO4, Li4Ti5O 12 and one or more of their respective modified materials.

[0086] During the charging and discharging process, solid-state battery cells undergo Li insertion / extraction and consumption, resulting in varying Li molar content at different discharge states. In this disclosure, the Li molar content listed for positive electrode active materials represents the initial state of the material, i.e., the state before material addition. As the positive electrode active material is applied to a solid-state battery cell, the Li molar content changes after charge-discharge cycles. Similarly, the O molar content listed for positive electrode active materials in this disclosure is only a theoretical value; lattice oxygen release causes changes in the O molar content, leading to fluctuations in the actual O molar content.

[0087] In some embodiments, the sulfide solid electrolyte contains sulfur atoms in its electrolyte composition, but is not limited to a specific composition, and may include one or more of crystalline solid electrolytes, amorphous solid electrolytes (glassy solid electrolytes), or glass-ceramic solid electrolytes.

[0088] In some embodiments, the sulfide solid electrolyte may include sulfide-germanium sulfide, binary sulfide, and ternary sulfide.

[0089] In some embodiments, sulfide of the silver-germanium type may include sulfides with the chemical formula Li 6±s P 1-j A j S 5±s - t B t X 1±s The material has the following properties: 0≤j<1, 0≤t<1, 0≤s<1. A includes one or more elements selected from Ge, Si, Sn, and Sb; B includes one or more elements selected from O, Se, and Te; and X includes one or more elements selected from Cl, Br, I, and F. Australite-type sulfides can include Li6PS5Cl.

[0090] In some embodiments, the binary sulfide may include one or more of Li2S-GeS2, Li2S-P2S5, Li2S-SiS2, and Li2S-B2S3.

[0091] In some embodiments, the ternary sulfide may include one or more of Li2S-SiS2-P2S5, Li2S-GeS2-P2S5, Li2S-SnS2-P2S5, and Li2S-AlS2-P2S5.

[0092] In some embodiments, the solid electrolyte may further include one or both of halide solid electrolytes and oxide solid electrolytes.

[0093] In some embodiments, the positive electrode film may further include a positive electrode conductive agent, which may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and vapor-grown carbon fibers (VGCF). For example, the positive electrode conductive agent may be vapor-grown carbon fibers.

[0094] The positive electrode may or may not include a positive electrode binder, depending on the manufacturing process of the positive electrode and the solid-state battery cell.

[0095] In some embodiments, the positive electrode sheet includes a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene oxide, fluorinated acrylate resins, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0096] In some embodiments, the current density of the positive electrode can be 1-5 mAh / cm². 2 .

[0097] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymer substrate and a metal material layer formed on at least one surface of the polymer substrate. As an example, the metal material in the metal material layer may be one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymer substrate may be one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0098] [Preparation Method of Composite Active Materials]

[0099] This disclosure provides a method for preparing a composite active material, comprising the following steps:

[0100] Provide materials including the kernel;

[0101] The core material and the coating material are mixed and then ball-milled to obtain a composite active material.

[0102] The composite active material includes a core and a coating layer, with the coating layer covering at least a portion of the core surface; the coating layer includes a selenium-containing compound with the chemical formula Se. a M b M includes at least one of Li, Na, K, Mg, Ca, S, Mo, Cr, Zn, In, Ga, Co and Mn, where 0 < a ≤ 5 and 0 < b ≤ 20.

[0103] Ball milling allows for the uniform coating of materials onto the core surface, thereby improving the uniformity of the coating layer. Furthermore, ball milling directly coats selenium compounds onto the core surface, increasing the purity of the selenium compounds in the coating layer and further enhancing the cycle stability and initial coulombic efficiency of solid-state battery cells.

[0104] In some embodiments, based on the total mass of the composite active material as 100%, the mass content of the selenium-containing compound can be 0.1%-10%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.5%, 3%, 3.5%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any range of the above values.

[0105] By setting the mass content of selenium-containing compounds in the coating layer within the aforementioned range, the thickness of the coating layer can be adjusted, the conductivity of the composite active material can be improved, thereby further enhancing the cycle stability and initial coulombic efficiency of the solid-state battery cell.

[0106] In some embodiments, the selenium-containing compound content can be 0.5%-2% based on the total mass of the composite active material (100%). This allows for adjustment of the coating thickness, further improving the conductivity of the composite active material, thereby further enhancing the cycle stability and initial coulombic efficiency of the solid-state battery cell.

[0107] In some embodiments, in the step of ball milling the mixture of the core material and the coating material, the ball milling speed can be 300-1000 rpm, for example, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, or any range of the above values.

[0108] In some embodiments, in the step of ball milling the mixture of the core material and the coating material, the ball milling time can be 3-9 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or any range of the above values.

[0109] Setting the ball milling speed and / or time within the above range can make the coating material more uniformly coated on the surface of the core.

[0110] In some embodiments, the step of ball milling the mixture of the core material and the coating material can be performed using an intermittent ball milling method.

[0111] Ball milling generates heat. Intermittent ball milling can dissipate this heat and reduce side reactions caused by excessively high temperatures during the ball milling process.

[0112] [Composite Active Materials]

[0113] The composite active material is prepared by the preparation method disclosed herein.

[0114] [Negative electrode plate and electrolyte plate]

[0115] In some embodiments, the solid-state battery cell further includes a negative electrode and an electrolyte sheet. The electrolyte sheet is located between the positive and negative electrode. The negative electrode includes a negative electrode active material, which may include one or more of the following: graphite, graphene, carbon nanotubes, mesophase microcarbon spheres, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, metal oxides, lithium metal, lithium alloys, and lithium composite materials.

[0116] Silicon-based materials may include one or more of elemental silicon, silicon oxides, silicon carbides, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin compounds, and tin alloys. Metal oxides may include one or more of TiO2, MoO2, In2O3, Al2O3, Cu2O, VO2, Ga2O3, Sb2O5, and Bi2O5. Other elements in lithium alloys may include one or more of In, Mg, Al, Zn, Sn, Ag, Au, Ga, Pt, and Fe, for example, Li-In alloys, Li-Mg alloys, Li-Al alloys, Li-Zn alloys, and Li-Fe alloys.

[0117] The negative electrode can be a metal sheet, such as a lithium sheet, which can be prepared by dry method or wet method.

[0118] In some embodiments, the negative electrode may further include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, carbon nanofibers, and vapor-grown carbon fibers (VGCF).

[0119] In some embodiments, the negative electrode sheet may further include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0120] The negative electrode sheet may or may not include a negative electrode current collector. In some embodiments, the negative electrode sheet includes a negative electrode current collector, with the negative electrode active material located on at least one surface of the negative electrode current collector. The negative electrode current collector may include a metal foil, a three-dimensional porous current collector, or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, nickel foil, nickel alloy foil, aluminum foil, and aluminum alloy foil. Examples of three-dimensional porous current collectors include copper mesh, nickel mesh, aluminum mesh, foamed copper, foamed nickel, and foamed aluminum. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer may include, but is not limited to, one or more of copper, copper alloy, aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0121] The electrolyte sheet includes a solid electrolyte. The solid electrolyte includes one or more of sulfide solid electrolytes, halide solid electrolytes, and oxide solid electrolytes. Optionally, the solid electrolyte includes a sulfide solid electrolyte. In this disclosure, the material of the solid electrolyte can refer to the selection of sulfide solid electrolytes, halide solid electrolytes, and oxide solid electrolytes in the above-described positive electrode sheet, and will not be repeated here.

[0122] Understandably, the coating layer can reduce the direct contact between the core and the sulfide solid electrolyte in the positive electrode, as well as the direct contact between the core and the sulfide solid electrolyte in the electrolyte sheet.

[0123] Solid-state battery cells can be prepared using methods known in the art. For example, the assembly methods of solid-state battery cells include, but are not limited to, coin cells, molded cells, hard-case cells, and pouch cells.

[0124] Example

[0125] The following examples describe the contents of this disclosure in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0126] Example 1

[0127] Preparation of composite active materials

[0128] SeS2 and LiNi were weighed according to a mass ratio of 0.5:99.5. 0.8 Co 0.1 Mn 0.1 The mixture of O2 (NCM811) was ball-milled at 500 rpm for a total of 6 hours, with a 5-minute break after every 10 minutes of milling. The resulting composite active material had a coating thickness of 5 nm.

[0129] Preparation of positive electrode sheet

[0130] The composite active material, sulfide solid electrolyte Li6PS5Cl, and vapor-grown carbon fiber (VGCF) positive electrode conductive agent prepared above were uniformly mixed at a mass ratio of 70:27:3 for 10 min to obtain composite positive electrode powder. Polytetrafluoroethylene (PTFE) positive electrode binder, equivalent to 1% of the total mass of the first three components, was added, and then rolled into a positive electrode film. Finally, the positive electrode film was hot-rolled and laminated with aluminum foil positive electrode current collector to obtain the positive electrode sheet. The thickness of the positive electrode sheet was 100 μm.

[0131] Preparation of solid-state battery cells

[0132] 100 mg of sulfide solid electrolyte Li6PS5Cl was weighed and added to a battery mold. The electrolyte sheet was obtained by pressing. Then, the positive electrode sheet was placed on one side of the electrolyte sheet, and InLi alloy was added to the other side as the negative electrode. The molar ratio of Li to In was 1:3. The solid battery cell was pressed into a solid battery cell under a pressure of 10 MPa and encapsulated in a mold battery fixture with an external pressure of 50 MPa.

[0133] Example 2

[0134] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0135] SeS2 and LiNi were weighed at a mass ratio of 1:99. 0.8 Co 0.1 Mn0.1 The mixture of O2 (NCM811) was ball-milled at 500 rpm for a total of 6 hours, with a 5-minute pause between every 10 minutes of milling. The resulting composite active material had a coating thickness of 10 nm.

[0136] Example 3

[0137] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0138] SeS2 and LiNi were weighed according to a mass ratio of 20:80. 0.8 Co 0.1 Mn 0.1 The mixture of O2 (NCM811) was ball-milled at 500 rpm for a total of 6 hours, with a 5-minute pause between every 10 minutes of milling. The resulting composite active material had a coating thickness of 200 nm.

[0139] Example 4

[0140] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0141] MoSe2 and LiNi were weighed at a mass ratio of 1:99. 0.8 Co 0.1 Mn 0.1 The mixture of O2 (NCM811) was ball-milled at 500 rpm for a total of 6 hours, with a 5-minute break after every 10 minutes of milling. The resulting composite active material had a coating thickness of 8 nm.

[0142] Example 5

[0143] Except for the following differences, the preparation method of the solid-state battery cell is the same as that in Example 1.

[0144] SeS2 and LiNi were weighed according to a mass ratio of 10:90. 0.8 Co 0.1 Mn 0.1 The mixture of O2 (NCM811) was ball-milled at 500 rpm for a total of 6 hours, with a 5-minute pause between every 10 minutes of milling. The resulting composite active material had a coating thickness of 100 nm.

[0145] Comparative Example 1

[0146] Except for not coating the positive electrode active material, the preparation method of the solid-state battery cell is the same as in Example 1.

[0147] Performance testing

[0148] (1) Performance testing of solid-state battery cells, materials or electrodes

[0149] Charge-discharge tests were conducted on the Blue Battery testing platform at temperatures of 25℃ and 60℃, with a charge-discharge voltage range of 2.6V-4.3V (vs. Li). + / Li), the external pressure during the test was 50MPa.

[0150] After three 0.1C charge-discharge cycles, a long-term 0.33C charge-discharge cycle test was conducted on a single solid-state battery cell. The initial charge-discharge specific capacity and initial coulombic efficiency at 0.1C were obtained by collecting and processing the first charge-discharge data at 0.1C. Initial coulombic efficiency (%) = (First discharge specific capacity / First charge specific capacity) × 100%. Dividing the discharge specific capacity of the 203rd cycle by the discharge specific capacity of the 4th cycle yielded the capacity retention rate after 200 cycles at 0.33C.

[0151] (2) Morphological analysis

[0152] SEM images of a uniform coating layer containing element Se observed on the surface of the positive electrode active material were obtained using a scanning electron microscope (Hitachi JSM 6700) and an energy dispersive spectroscopy (EDS) instrument attached to the SEM instrument.

[0153] The thickness and uniformity of the coating layer can be observed using high-resolution transmission electron microscopy (HRTEM).

[0154] The test results of Examples 1-5 and Comparative Example 1 are shown in Table 1.

[0155] Table 1

[0156]

[0157] As can be seen from the test results in Table 1, the composite active material of this embodiment utilizes the good compatibility between the selenium-containing compound coating layer and the sulfide solid electrolyte to reduce the direct contact between the core and the sulfide solid electrolyte, reduce the decomposition of the sulfide solid electrolyte, and improve the cycle stability and first coulombic efficiency of the solid battery cell.

[0158] It should be noted that this disclosure is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this disclosure are included within the technical scope of this disclosure. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, are also included within the scope of this disclosure without departing from the spirit of this disclosure.

Claims

1. A solid-state battery cell, characterized in that, It includes a current collector and a membrane layer disposed on at least one side surface of the current collector, the membrane layer comprising a composite active material and a sulfide solid electrolyte; The composite active material includes a core and a coating layer, wherein the coating layer covers at least a portion of the surface of the core. The coating layer comprises a selenium-containing compound with the chemical formula Se. a M b M includes at least one of Li, Na, K, Mg, Ca, S, Mo, Cr, Zn, In, Ga, Co and Mn, where 0 < a ≤ 5 and 0 < b ≤ 20.

2. The solid-state battery cell according to claim 1, characterized in that, The selenium-containing compounds include one or more of sulfur selenium compounds, molybdenum selenium compounds, and antimony selenium compounds.

3. The solid-state battery cell according to claim 2, characterized in that, The sulfur-selenium compounds include SeS2, Se5S, SeS, Se5S2, Se3S2, Se3S5, SeS7, and SeS. 20 One or more of them.

4. The solid-state battery cell according to any one of claims 1-3, characterized in that, Based on the total mass of the composite active material as 100%, the mass content of the selenium-containing compound is 0.5%-5%, optionally 0.5%-2%.

5. The solid-state battery cell according to any one of claims 1-4, characterized in that, The thickness of the coating layer is 1-100 nm.

6. The solid-state battery cell according to any one of claims 1-5, characterized in that, The thickness of the coating layer is 5-20 nm.

7. The solid-state battery cell according to any one of claims 1-6, characterized in that, The composite active material satisfies one or more of the following conditions (1)-(5): (1) The specific surface area of ​​the composite active material is 1.3-3.5 m². 2 / g; (2) The volume particle size distribution Dv50 of the composite active material is 2-8 μm; (3) The electronic conductivity of the composite active material is 8-18 mS / cm, and the ionic conductivity of the composite active material is 0.1-1 mS / cm; (4) The compaction density of the composite active material is 1-3 g / cm³. 3 ; (5) The electronic conductivity of the coating layer is 0.1-1 mS / cm, and the ionic conductivity of the coating layer is 0.01-0.1 mS / cm.

8. A method for preparing a composite active material, characterized in that, include: Provide materials including the kernel; The core material and the coating material are mixed and then ball-milled to obtain a composite active material. The composite active material comprises a core and a coating layer, wherein the coating layer coats at least a portion of the surface of the core; the coating layer comprises a selenium-containing compound with the chemical formula Se. a M b M includes at least one of Li, Na, K, Mg, Ca, S, Mo, Cr, Zn, In, Ga, Co and Mn, where 0 < a ≤ 5 and 0 < b ≤ 20.

9. The preparation method according to claim 8, characterized in that, Based on the total mass of the composite active material being 100%, the mass content of the selenium-containing compound is 0.1%-10%.

10. The preparation method according to claim 8 or 9, characterized in that, Based on the total mass of the composite active material being 100%, the mass content of the selenium-containing compound is 0.5%-2%.

11. The preparation method according to any one of claims 8-10, characterized in that, In the step of ball milling the mixture of the core material and the coating material, the ball milling process satisfies one or more of the following conditions (1)-(3): (1) The ball milling speed is 300-1000 rpm; (2) The ball milling process takes 3-9 hours; (3) The ball milling process is carried out by intermittent ball milling.

12. A composite active material, characterized in that, The composite active material is prepared by any one of the preparation methods according to claims 8-11.

13. A battery device, characterized in that, It includes any one of the solid-state battery cells according to claims 1-7.

14. An electrical appliance, characterized in that, Includes the battery device as described in claim 13.

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